CVE-2019-19234

When an account is disabled via the shadow file, by replacing the password hash with "!", it is not considered disabled by sudo. And depending on the configuration, sudo can be run by using such disabled account.

The new runas_check_shell sudoers setting can be used to require that the runas user have a shell listed in the /etc/shells file. On many systems, users such as bin, do not have a valid shell and this flag can be used to prevent commands from being run as those users.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

This flaw basically allows users which have disabled account in /etc/shadow (password is replaced with '!) to have sudo access. Systems not having such disabled account, or systems disabling sudo access for such accounts using other means (such as not allowing such users to run sudo via access control mechanisms) are not affected by this flaw.